I recently bought the bobbin genie teflon washers that you add to your bobbin when FMQ. I got the large size for my tin lizzie and the smaller size for my regular sewing machine. So far I like them for my tin lizzie. I haven't tried them in my reg sewing machine. They say they eliminate birdsnests on the back of the quilt when changing directions when FMQ.Has anyone else ever used them? how did you like them?